The present invention relates to a resonant pick-up system for a stringed instrument and in particular, to a composite piezo-electric transducer bridge assembly for violins and similar string instruments.
Piezo-electric amplification of the sound produced by vibrating strings has become common, especially as adapted to guitar and hand plucking type instruments, as will be seen from the following patents: 2,222,057; 3,113,990; 3,178,501; 3,291,887; 3,325,580; 3,453,920; 3,712,951; 4,147,084; 4,314,495; 4,356,754; 4,491,051; 4,567,805.
A common approach is to compressively engage a piezo element, (or elements) between the saddle, which supports the strings, and the saddle mounting structure which lies on the instrument top. This is essentially a contact microphone arrangement directly beneath the strings and the piezo element is responsive, in common, to all the strings. The response of the piezo element being determined by a vibrational response of the materials it is sandwiched between. While this generally produces the desired result, there are some problems with this approach. One major problem being a susceptibility to an electro-harmonic feedback loop occurring through the amplification system due to the instrument body acting as a large microphonic surface. The electrical output of the piezo elements are also limited due to the compressive restraints on the elements. Also, an unbalanced output from string to string due to varying string size-amplitude relationships.
The application of piezo-electric elements to violins or similar instruments, such as the cello and bass require a different approach than that of the guitar. A violin bridge with its thin, high structure, supported by two small feet and balanced on the instrument top by the pressure of the tightened strings seated upon it, does not lend itself to an effective compressive mounting of piezo elements near the strings. While a guitar, with its short saddle structure close to the top of the instrument, easily accommodates the placement of piezo elements under the saddle in close proximity to the strings, orientated on a flat surface parallel with the plane of the instrument body's top surface. The violin requires a different orientation of the transducer elements to retain the proportions of bridge to body size. As already stated, the bridge structure is very thin and high above the instrument body. This limits the arrangement wherein a single piezo element or even multiple elements can interact with any given vibrating string with sufficient isolation from the violin body, and from the other strings, to produce a clear strong signal.
An object of the invention is to provide an acoustically coupled transducer system with excellent inherent harmonic qualities which is capable of transforming the dissimilar vibratory motions of bowed or plucked strings into electrical signals.
It is a further object of the invention to provide an acoustically coupled pick-up system capable of producing a flat, uniform response, while minimizing unwanted resonances and instrument body noise.
The purpose of this invention is to provide an efficient electro-mechanical coupling between each musical instrument string and an associated piezo-electric transducer element, in a multiple stringed instrument. This produces a high fidelity audio signal for amplification, equally from all the strings.
The above and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following disclosure.